1. Field of the Invention
This invention relates to an apparatus which stabilizes an operator-held optical system against rotational vibration and thus improves the steadiness of the optical image produced by the system. The stabilizer finds application with cameras, binoculars, sighted hand weapons and other operator-held optical devices.
2. Background Information
Optical devices such as motion picture, video and still cameras, binoculars, telescopes and sighted hand weapons must be held steady when in use. One way to accomplish this is to mount the optical device on a tripod or other rigid structure. Many times, however, it is desirable that the optical device be freely mobile, for example for hand-held operation. As many optical devices are becoming increasingly miniaturized, there is a trend toward this mobile mode of operation. In such settings the device can be moved and rotated but will be subject to undesirable rotational vibration in all three axes. This vibration or "shake" exhibits itself as an unsteady image that becomes more pronounced at extreme conditions of magnification and the like.
Various mechanisms have been described for reducing this vibration while allowing mobility. U.S. Pat. Nos. 4,158,488, 4,158,489 and 4,158,490, issued on June 19, 1979, to Gottschalk describe a body harness mount for motion picture cameras which employs pneumatic cushions to damp unwanted movements of the camera. U.S. Pat. No. 4,206,983, issued June 10, 1980, to Nettman et al, shows a harness type mobile camera stabilizing mount which relies upon positioning the weight of the camera low on the operator's hips to minimize shake. U.S. Pat. No. 4,394,075, issued July 19, 1983, to Brown et al, relies upon an operator harness torso mounting of the camera and a flexible camera support arm to damp vibrations. U.S. Pat. No, 4,474,439, issued Oct. 2, 1984, to Brown, describes camera stabilizing systems known in the motion picture trade as the "Steadicam" system. Steadicam was described in the SMPTE Journal, 87:587-91, Summer 1978. It was also discussed in Industrial Photography, issues of March 1980 and January 1984.
The Steadicam uses an arm with "lazy daisy" linkages which is connected at one end to the camera platform and at the other to a vest worn by the operator. This gives the camera free motion as the arm extends or retracts but does not allow it to rotate. Effectively, the operator's body is the base of a "tripod". Further, the arm contains springs that transfer the weight of the camera to the vest and let the operator's arm direct the camera without supporting it.
These stabilizers are expensive and cumbersome and unsuited for the miniature scale equipment increasingly being used professionally and the small cameras and the like commonly used by amateurs.
U.S. Pat. No. 3,858,228, issued Dec. 31, 1974, to Mito, describes a stabilizing unit of a size applicable to small cameras. The Mito device employs one or more gyroscopes to stabilize the camera. Such a system is not ideal. Gyroscopes are expensive and must be highly precise if they are not to contribute vibrations of their own. They take appreciable time to reach their useful rate of rotation. Moreover, rather than merely damping vibration, they lock the camera in a set direction such that to move the camera to another direction, that is to adjust the angle to which the camera is aimed, the camera must be decoupled from the gyroscopes and then reclamped or the gyroscopes must be temporarily stopped. This interferes with adjustments or with panning of the camera.
It is an object of this invention to provide a mechanism for stabilizing an optical system such as a camera, which mechanism is compact and permits panning and aiming of the optical system.